U.S. patent application number 13/961456 was filed with the patent office on 2014-02-13 for solid-state imaging device and imaging apparatus.
This patent application is currently assigned to OLYMPUS CORPORATION. The applicant listed for this patent is OLYMPUS CORPORATION. Invention is credited to Jun Aoki.
Application Number | 20140042577 13/961456 |
Document ID | / |
Family ID | 50065583 |
Filed Date | 2014-02-13 |
United States Patent
Application |
20140042577 |
Kind Code |
A1 |
Aoki; Jun |
February 13, 2014 |
SOLID-STATE IMAGING DEVICE AND IMAGING APPARATUS
Abstract
A first substrate has a plurality of photoelectric conversion
units arranged in two dimensions. A second substrate has a
plurality of photoelectric conversion units arranged in two
dimensions. A plurality of photoelectric conversion units are
arranged in a region of the second substrate corresponding to a
region of the first substrate where one photoelectric conversion
unit is arranged. The imaging signals based on signal charges
stored in the photoelectric conversion units and the light field
signals based on signal charges stored in the photoelectric
conversion units are read.
Inventors: |
Aoki; Jun; (Tokyo,
JP) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
OLYMPUS CORPORATION |
Tokyo |
|
JP |
|
|
Assignee: |
OLYMPUS CORPORATION
Tokyo
JP
|
Family ID: |
50065583 |
Appl. No.: |
13/961456 |
Filed: |
August 7, 2013 |
Current U.S.
Class: |
257/432 ;
257/443 |
Current CPC
Class: |
H01L 27/14627 20130101;
H01L 27/14634 20130101; H01L 27/14636 20130101; H01L 27/14629
20130101; H01L 27/14612 20130101; H01L 27/1461 20130101; H01L
27/14621 20130101 |
Class at
Publication: |
257/432 ;
257/443 |
International
Class: |
H01L 27/146 20060101
H01L027/146 |
Foreign Application Data
Date |
Code |
Application Number |
Aug 10, 2012 |
JP |
2012-178741 |
Claims
1. A solid-state imaging device comprising: a first substrate which
has a plurality of first photoelectric conversion units arranged in
two dimensions; a second substrate which has a plurality of second
photoelectric conversion units arranged in two dimensions and is
stacked on the first substrate; and a selector which selects the
angle of a light ray that is transmitted through the first
substrate and is incident on the second photoelectric conversion
units, wherein the plurality of second photoelectric conversion
units are arranged in a region of the second substrate
corresponding to a region of the first substrate where one first
photoelectric conversion unit among the plurality of first
photoelectric conversion units is arranged, and wherein imaging
signals based on signal charges stored in the first photoelectric
conversion units are read and light field signals based on signal
charges stored in the second photoelectric conversion units are
read.
2. The solid-state imaging device according to claim 1, wherein the
first substrate further includes a transmission unit that transfers
the signal charges to the second substrate, and wherein the second
substrate further includes: a first reading unit that reads the
imaging signals transferred by the transmission unit; and a second
reading unit that reads the light field signals.
3. The solid-state imaging device according to claim 1, further
comprising: a third substrate, wherein the first substrate further
includes a first transmission unit that transfers the signal
charges to the second substrate, wherein the second substrate
further includes: a second transmission unit that transfers the
signal charges transferred by the first transmission unit to the
third substrate; and a third transmission unit that transfers the
signal charges stored in the second photoelectric conversion units
to the third substrate, and wherein the third substrate includes: a
first reading unit that reads the imaging signals based on the
signal charges transferred by the second transmission unit; and a
second reading unit that reads the light field signals based on the
signal charges transferred by the third transmission unit.
4. The solid-state imaging device according to claim 1, wherein the
selector includes: a micro lens that is provided on the first
substrate and condenses light incident on the first photoelectric
conversion units; and a light pipe that is provided at the first
substrate and guides the light condensed by the micro lens to a
region of the second substrate where the second photoelectric
conversion units are arranged.
5. The solid-state imaging device according to claim 2, wherein the
selector includes: a micro lens that is provided on the first
substrate and condenses light incident on the first photoelectric
conversion units; and a light pipe that is provided at the first
substrate and guides the light condensed by the micro lens to a
region of the second substrate where the second photoelectric
conversion units are arranged.
6. The solid-state imaging device according to claim 3, wherein the
selector includes: a micro lens that is provided on the first
substrate and condenses light incident on the first photoelectric
conversion units; and a light pipe that is provided at the first
substrate and guides the light condensed by the micro lens to a
region of the second substrate where the second photoelectric
conversion units are arranged.
7. The solid-state imaging device according to claim 4, wherein the
light pipe is an insulator.
8. The solid-state imaging device according to claim 5, wherein the
light pipe is an insulator.
9. The solid-state imaging device according to claim 6, wherein the
light pipe is an insulator.
10. An imaging apparatus comprising: a solid-state imaging device
including: a first substrate which has a plurality of first
photoelectric conversion units arranged in two dimensions; a second
substrate which has a plurality of second photoelectric conversion
units arranged in two dimensions and is stacked on the first
substrate; and a selector which selects the angle of a light ray
that is transmitted through the first substrate and is incident on
the second photoelectric conversion units, wherein the plurality of
second photoelectric conversion units are arranged in a region of
the second substrate corresponding to a region of the first
substrate where one first photoelectric conversion unit among the
plurality of first photoelectric conversion units is arranged, and
wherein imaging signals based on signal charges stored in the first
photoelectric conversion units are read and light field signals
based on signal charges stored in the second photoelectric
conversion units are read.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] The present invention relates to a solid-state imaging
device that has a plurality of substrates and acquires imaging
signals and light field signals, and an imaging apparatus that
includes the solid-state imaging device.
[0003] Priority is claimed on Japanese Patent Application No.
2012-178741, filed Aug. 10, 2012, the contents of which are
incorporated herein by reference.
[0004] 2. Description of Related Art
[0005] In recent years, generally, video cameras, electronic still
cameras, or the like have been widely prevalent. Charge coupled
device (CCD) type or amplified solid-state imaging devices are used
for these cameras. The amplified solid-state imaging devices guide
a signal charge, which is generated and stored by a photoelectric
conversion unit of a pixel on which light is incident, to an
amplifying unit provided in the pixel, and output a signal, which
is amplified by the amplifying unit, from the pixel. In the
amplified solid-state imaging devices, a plurality of such pixels
are arranged in a two-dimensional matrix. In the amplified
solid-state imaging devices, for example, a CMOS type solid-state
imaging device using complementary metal oxide semiconductor (CMOS)
transistors is known.
[0006] Additionally, a solid-state imaging device aiming at not
only obtaining imaging signals on the CMOS type solid-state imaging
device but also at obtaining light field signals to obtain the
depth information on a subject is disclosed in the specification of
U.S. Pat. No. 8,155,456. In the specification of U.S. Pat. No.
8,155,456, pixels for obtaining the imaging signals and pixels for
obtaining the light field signals are the same.
SUMMARY OF THE INVENTION
[0007] A solid-state imaging device related to a first aspect of
the present invention includes a first substrate that has a
plurality of first photoelectric conversion units arranged in two
dimensions; a second substrate that has a plurality of second
photoelectric conversion units arranged in two dimensions and is
stacked on the first substrate; and a selector that selects the
angle of a light ray that is transmitted through the first
substrate and is incident on the second photoelectric conversion
units. The plurality of second photoelectric conversion units are
arranged in a region of the second substrate corresponding to a
region of the first substrate where one first photoelectric
conversion unit among the plurality of first photoelectric
conversion units is arranged, and imaging signals based on signal
charges stored in the first photoelectric conversion units are read
and light field signals based on signal charges stored in the
second photoelectric conversion units are read.
[0008] According to a second aspect of the present invention, in
the first aspect, the first substrate may further include a
transmission unit that transfers the signal charges stored in the
first photoelectric conversion units to the second substrate, and
the second substrate may further include a first reading unit that
reads the imaging signals based on the signal charges transferred
by the transmission unit, and a second reading unit that reads the
light field signals based on the signal charges stored in the
second photoelectric conversion units.
[0009] According to a third aspect of the present invention, in the
first aspect, the solid-state imaging device may further include a
third substrate, the first substrate may further include a first
transmission unit that transfers the signal charges stored in the
first photoelectric conversion units to the second substrate, the
second substrate may further include a second transmission unit
that transfers the signal charges transferred by the first
transmission unit to the third substrate; and a third transmission
unit that transfers the signal charges stored in the second
photoelectric conversion units to the third substrate, and the
third substrate may include a first reading unit that reads the
imaging signals based on the signal charges transferred by the
second transmission unit; and a second reading unit that reads the
light field signals based on the signal charges transferred by the
third transmission unit.
[0010] According to a fourth aspect of the present invention, in
any one of the first aspect to third aspect, the selector may
include a micro lens that is provided on the first substrate and
condenses light incident on the first photoelectric conversion
units; and a light pipe that is provided at the first substrate and
guides the light condensed by the micro lens to a region of the
second substrate where the second photoelectric conversion units
are arranged.
[0011] According to a fifth aspect of the present invention, in the
fourth aspect, the light pipe may be an insulator.
[0012] A solid-state imaging device related to a sixth aspect of
the present invention includes a first substrate that has a
plurality of first photoelectric conversion units arranged in two
dimensions; a second substrate that has a plurality of second
photoelectric conversion units arranged in two dimensions and is
stacked on the first substrate; and a selector that selects the
angle of a light ray that is transmitted through the first
substrate and is incident on the second photoelectric conversion
units. The plurality of second photoelectric conversion units are
arranged in a region of the second substrate corresponding to a
region of the first substrate where one first photoelectric
conversion unit among the plurality of first photoelectric
conversion units is arranged, and imaging signals based on signal
charges stored in the first photoelectric conversion units are read
and light field signals based on signal charges stored in the
second photoelectric conversion units are read.
BRIEF DESCRIPTION OF THE DRAWINGS
[0013] FIG. 1 is a partial cross-sectional view of a solid-state
imaging device according to the first embodiment of the present
invention.
[0014] FIG. 2 is a partial plan view of the solid-state imaging
device according to the first embodiment of the present
invention.
[0015] FIG. 3 is a partial cross-sectional view of the solid-state
imaging device according to the first embodiment of the present
invention.
[0016] FIG. 4 is a partial cross-sectional view of a solid-state
imaging device according to a second embodiment of the present
invention.
[0017] FIG. 5 is a partial plan view of the solid-state imaging
device according to the second embodiment of the present
invention.
[0018] FIG. 6 is a block diagram showing the configuration of an
imaging apparatus according to a third embodiment of the present
invention.
DETAILED DESCRIPTION OF THE INVENTION
[0019] Embodiments of the present invention will be described below
referring to the drawings.
First Embodiment
[0020] A first embodiment of the present invention will be
described hereinafter. FIG. 1 shows the configuration of a
solid-state imaging device 100 according to the present embodiment
in a cross-sectional view. The solid-state imaging device 100 is
configured to have a first substrate 110 where a plurality of
photoelectric conversion units 115 (first photoelectric conversion
units) are formed, and a second substrate 120 where a plurality of
photoelectric conversion units 125 (second photoelectric conversion
units), MOS transistors for reading signals, and the like are
formed. The first substrate 110 and the second substrate 120 have a
stacked structure, the stacked structure is that the first
substrate 110 is overlapped on the second substrate 120, and are
overlapped on each other and bonded together so that mutual
principal surfaces face each other. Light is incident from the
upper side (first substrate 110 side) of FIG. 1. The solid-state
imaging device 100 has a micro lens 101 (selector) that images the
light from a subject, and the micro lens 101 is provided on the
front surface of the first substrate 110. Additionally, a color
filter 102 corresponding to a predetermined color is formed between
the first substrate 110 and the micro lens 101.
[0021] As shown in FIG. 1, the first substrate 110 is configured to
have a semiconductor substrate 111 where the photoelectric
conversion units 115 and a floating diffusion layer 118 are formed,
and a multilayer wiring layer. The multilayer wiring layer has an
insulating film 112, a wiring layer 113, a via 114, a light pipe
116 (selector), and a transfer transistor 117 (gate electrode). The
photoelectric conversion units 115 are, for example, buried
photodiodes configured by an N-type well that is formed in a P-type
well layer and a P+-type impurity region that has contact with the
N-type well and is formed on the surface side of the P-type well
layer.
[0022] The wiring layer 113 is stacked via the insulating film 112,
and forms the multilayer wiring layer by connecting respective
wiring layers by means of the via 114. In FIG. 1, four wiring
layers 113 are formed. Since the wiring layers 113 are used for
transmission of signals within the first substrate 210 or supply of
a power-source voltage or a ground voltage, the wiring layers are
made of materials (for example, metals, such as aluminum and
copper) that have conductivity. A plurality of the light pipes 116
are provided for one photoelectric conversion unit 115, and are
formed so as to pass through the insulating film 112. The light
pipes 116 are dielectric bodies (insulators) that have a refractive
index different from the insulating film 112. The transfer
transistor 117 and the via 114 function as a transmission unit that
transfers a signal charge stored in a photoelectric conversion unit
115 to the second substrate 120.
[0023] As shown in FIG. 1, the second substrate 120 is configured
to have a semiconductor substrate 121 where the photoelectric
conversion units 125 and floating diffusion layers 127, 129, and
131 are formed, and a multilayer wiring layer. A multilayer wiring
layer-insulating film 122, wiring layers 123 and 133, vias 124 and
132, a light pipe 126, and a transfer transistor 128 (gate
electrode) are formed. The photoelectric conversion units 125 are,
for example, photodiodes similar to the photoelectric conversion
units 115. A plurality of photoelectric conversion units 125 are
provided corresponding to one photoelectric conversion unit
115.
[0024] The wiring layer 123 is stacked via the insulating film 122,
and forms the multilayer wiring layer by connecting respective
wiring layers by means of the via 124. In FIG. 1, three wiring
layers 123 are formed. Since the wiring layers 123 are used for
transmission of signals within the second substrate 120 or supply
of a power-source voltage or a ground voltage, the wiring layers
are made of materials (for example, metals, such as aluminum and
copper) that have conductivity. The via 124 is electrically
connected to the via 114 of the first substrate 110 at an interface
between the first substrate 110 and the second substrate 120. The
via 124 transfers the signal charge, which is transferred from the
first substrate 110 to the second substrate 120, to the floating
diffusion layer 127. The transfer transistor 128 configures a
reading unit (first reading unit) for reading an imaging signal
based on the signal charge transferred to the floating diffusion
layer 127, from the second substrate 120.
[0025] The light pipes 126 are provided for the light pipes 116 in
one-to-one correspondence and are formed so as to pass through the
insulating film 122. Additionally, the light pipes 126 are provided
for the photoelectric conversion units 125 in one-to-one
correspondence. The light pipes 126 are dielectric bodies
(insulators) that have a refractive index different from the
insulating film 122. Preferably, the light pipes 126 are formed of
the same material as the light pipe 116. The light pipes 116 and
126 function as waveguides that guide light, which is incident on
the solid-state imaging device 100, to the photoelectric conversion
units 125. The transfer transistor 130, the via 132, and the wiring
layer 133 configure a reading unit (second reading unit) for
reading a light field signal based on a signal charge stored in a
photoelectric conversion unit 125, from the second substrate
120.
[0026] FIG. 2 shows a state where only a portion equivalent to four
pixels of the solid-state imaging device 100 shown in FIG. 1 is
seen in plan view. Four pixels are arranged in a two-dimensional
matrix. One micro lens 101 and one color filter 102 are arranged in
a region corresponding to one pixel. When seen from the incidence
side of light, one photoelectric conversion unit 115 is arranged
inside a region where the micro lens 101 is arranged. Additionally,
a plurality of photoelectric conversion units 125 are arranged in a
region where the photoelectric conversion unit 115 is arranged. In
FIG. 2, the photoelectric conversion units 125 of 6 rows and 6
columns are arranged for one micro lens 101.
[0027] Light incident on the solid-state imaging device 100 is
condensed by the micro lens 101 and is incident on the
photoelectric conversion unit 115 via the color filter 102. This
light is photoelectrically converted by the photoelectric
conversion unit 115, and a signal charge according to the quantity
of light is generated. The signal charge generated by the
photoelectric conversion unit 115 is transferred to the floating
diffusion layer 118 via the transfer transistor 117. The signal
charge transferred to the floating diffusion layer 118 is
transferred to the floating diffusion layer 127 via the multilayer
wiring layer of the first substrate 110 and the multilayer wiring
layer of the second substrate 120. The signal charge transferred to
the floating diffusion layer 127 is transferred to the floating
diffusion layer 129 via the transfer transistor 128, is turned into
a voltage signal by a circuit (not shown), and is output as an
imaging signal.
[0028] Additionally, a portion of light incident on the solid-state
imaging device 100 is transmitted through the first substrate 110
and the insulating film 122 of the second substrate 120 via the
light pipes 116 and 126, and is incident on a photoelectric
conversion unit 125 of the second substrate 120.
[0029] This light is photoelectrically converted by the
photoelectric conversion unit 125, and a signal charge according to
the quantity of light is generated. The signal charge generated by
the photoelectric conversion unit 125 is transferred to the
floating diffusion layer 131 via the transfer transistor 130. The
signal charge transferred to the floating diffusion layer 131 is
transferred via the via 132 and the wiring layer 133, is turned
into a voltage signal by a circuit (not shown), and is output as a
light field signal.
[0030] A portion of light that is incident on the solid-state
imaging device 100 and that is transmitted through the micro lens
101 and the color filter 102 is incident on a light pipe 116
provided at a position according to the angle of incidence on the
micro lens 101. For example, as shown in FIG. 3, a light ray 150
incident on the micro lens 101 at a first incidence angle, and a
light ray 151 incident on the micro lens 101 at a second incidence
angle are refracted by the micro lens 101, and are incident on
different light pipes 116 according to the respective incidence
angles. Selecting the light incident on the photoelectric
conversion units 125 in two dimensions by the micro lens 101 and
the light pipes 116 is equal to selecting the light ray angles of
the light incident on the solid-state imaging device 100. Hence, a
signal obtained by a photoelectric conversion unit 125 corresponds
to the light ray angle of the light incident on the solid-state
imaging device 100.
[0031] As described above, according to the present embodiment, the
photoelectric conversion unit 115 for obtaining the imaging signal
and the photoelectric conversion unit 125 for obtaining the light
field signal are arranged on different substrates, respectively.
Thus, it is possible to form the photoelectric conversion units 115
with a sufficient size to obtain the imaging signal.
[0032] For this reason, the light field signal can be acquired
without sacrificing the S/N ratio of the imaging signal.
[0033] Additionally, the imaging signal can be read via the
transfer transistor 128 provided at the second substrate 120.
Additionally, the light field signal can be read via the transfer
transistor 130, the via 132, and the wiring layer 133 provided at
the second substrate 120. Moreover, as the light pipes 116 and 126
are provided, light can be guided to the photoelectric conversion
unit 125 while reducing the crosstalk of light incident on the
solid-state imaging device 100. Moreover, the light pipes 116 and
126 can be realized by a post-process of a semiconductor process by
forming the light pipes 116 and 126 of insulators.
Second Embodiment
[0034] Next, a second embodiment of the present invention will be
described. FIG. 4 shows the configuration of a solid-state imaging
device 200 according to the present embodiment in a cross-sectional
view. The solid-state imaging device 200 is configured to have a
first substrate 210 where a plurality of photoelectric conversion
units 215 (first photoelectric conversion units) are formed, a
second substrate 220 where a plurality of photoelectric conversion
units 225 (second photoelectric conversion units) are formed, and a
third substrate 230 where a plurality of MOS transistors for
reading signals are formed. The first substrate 210, the second
substrate 220, and the third substrate 230 have a stacked
structure, and are overlapped on each other and bonded together so
that mutual principal surfaces face each other. Light is incident
from the upper side in the drawing, and a micro lens 201 that
images the light from a subject and a color filter 202
corresponding to a predetermined color are formed on the surface of
the first substrate 210.
[0035] As shown in FIG. 4, the first substrate 210 is configured to
have a semiconductor substrate 211 where the photoelectric
conversion units 215 and a floating diffusion layer 218 are formed,
and a multilayer wiring layer. The multilayer wiring layer has an
insulating film 212, a wiring layer 213, a via 214, a light pipe
216 (selector), and a transfer transistor 217 (gate electrode). The
photoelectric conversion units 215 are, for example, embedded
photodiodes configured by an N-type well that is formed in a P-type
well layer and a P+-type impurity region that has contact with the
N-type well and is formed on the surface side of the P-type well
layer.
[0036] The wiring layer 213 is stacked via the insulating film 212,
and forms the multilayer wiring layer by connecting respective
wiring layers by means of the via 214. In FIG. 4, four wiring
layers 213 are formed. Since the wiring layers 213 are used for
transmission of signals within the first substrate 210 or supply of
a power-source voltage or a ground voltage, the wiring layers are
made of materials (for example, metals, such as aluminum and
copper) that have conductivity. A plurality of the light pipes 216
are provided for one photoelectric conversion unit 225, and are
formed so as to pass through the insulating film 212. The light
pipes 216 are dielectric bodies (insulators) that have a refractive
index different from the insulating film 212. The light pipes 216
function as waveguides that guide light, which is incident on the
solid-state imaging device 200, to the photoelectric conversion
units 225. The transfer transistor 217 and the via 214 function as
a transmission unit (first transmission unit) that transfers a
signal charge stored in a photoelectric conversion unit 215 to the
second substrate 120.
[0037] As shown in FIG. 4, the second substrate 220 is configured
by a semiconductor substrate 221 where the photoelectric conversion
units 225 and a through via 226 are formed, and a multilayer wiring
layer where an insulating film 222, wiring layers 223, and a via
224 are formed. The photoelectric conversion units 225 are, for
example, photodiodes similarly to the photoelectric conversion
units 215. A plurality of photoelectric conversion units 225 are
provided corresponding to one photoelectric conversion unit
215.
[0038] The through via 226 is electrically connected to the via 214
of the first substrate 210 at an interface between the first
substrate 210 and the second substrate 220, and is electrically
connected to the via 224 of the second substrate 220 at an
interface between the semiconductor substrate 211 and the
insulating film 222. The through via 226 is insulated from the
semiconductor substrate 221.
[0039] The wiring layer 223 is stacked via the insulating film 222,
and forms the multilayer wiring layer by connecting respective
wiring layers by means of the via 224. In FIG. 4, three wiring
layers 223 are formed. Since the wiring layers 223 are used for
transmission of signals within the second substrate 220 or supply
of a power-source voltage or a ground voltage, the wiring layers
are made of materials (for example, metals, such as aluminum and
copper) that have conductivity. The multilayer wiring layer
including the insulating film 222, the wiring layers 223, and the
via 224 has a multilayer wiring layer that transfers the signal
charge generated by the photoelectric conversion unit 215, and a
multilayer wiring layer that transfers a signal charge generated by
a photoelectric conversion unit 225. The through via 226 functions
as a transmission unit (second transmission unit) that transfers
the signal charge transferred from the first substrate 210, to the
third substrate 230. The via 224 functions as a transmission unit
(third transmission unit) that transfers the signal charge
generated by the photoelectric conversion unit 225, to the third
substrate 230.
[0040] As shown in FIG. 4, the third substrate 230 is configured to
have a semiconductor substrate 231 where floating diffusion layers
235, 237, 238, and 240 are formed, and a multilayer wiring layer.
The multilayer wiring layer has an insulating film 232, a wiring
layer 233, a via 234, and transfer transistors 236 and 239 (gate
electrodes). The wiring layer 233 is stacked via the insulating
film 232, and forms the multilayer wiring layer by connecting
respective wiring layers by means of the via 234. In FIG. 4, three
wiring layers 233 are formed. Since the wiring layers 233 are used
for transmission of signals within the third substrate 230 or
supply of a power-source voltage or a ground voltage, the wiring
layers are made of materials (for example, metals, such as aluminum
and copper) that have conductivity. The via 234 and the via 224 are
electrically connected to each other at an interface between the
second substrate 220 and the third substrate 230. The multilayer
wiring layer including the insulating film 232, the wiring layers
233, and the via 234 has a multilayer wiring layer that transfers
the signal charge generated by the photoelectric conversion unit
215, and a multilayer wiring layer that transfers the signal charge
generated by the photoelectric conversion unit 225.
[0041] The transfer transistor 236 configures a reading unit (first
reading unit) for reading an imaging signal based on the signal
charge transferred to the floating diffusion layer 235, from the
third substrate 230. Additionally, the transfer transistor 239
configures a reading unit (second reading unit) for reading the
light field signal based on the signal charge stored in the
photoelectric conversion unit 225, from the third substrate
230.
[0042] FIG. 5 shows a state where only a portion equivalent to four
pixels of the solid-state imaging device 200 shown in FIG. 4 is
seen in a plan view. Four pixels are arranged in a two-dimensional
matrix. One micro lens 201 and one color filter 202 are arranged in
a region corresponding to one pixel. When seen from the incidence
side of light, one photoelectric conversion unit 215 is arranged
inside a region where the micro lens 201 is arranged. Additionally,
a plurality of photoelectric conversion units 225 are arranged in a
region where the photoelectric conversion unit 215 is arranged. In
FIG. 5, the photoelectric conversion units 225 of 6 rows and 6
columns are arranged for one micro lens 201.
[0043] Light incident on the solid-state imaging device 200 is
condensed by the micro lens 201 and is incident on the
photoelectric conversion unit 215. This light is photoelectrically
converted by the photoelectric conversion unit 215, and a signal
charge according to the quantity of light is generated. The signal
charge generated by the photoelectric conversion unit 215 is
transferred to the floating diffusion layer 218 via the transfer
transistor 217. The signal charge transferred to the floating
diffusion layer 218 is transferred to the floating diffusion layer
235 via the multilayer wiring layer of the first substrate 210, the
through via 226 and multilayer wiring layer of the second substrate
220, and the multilayer wiring layer of the third substrate 230.
The signal charge transferred to the floating diffusion layer 235
is transferred to the floating diffusion layer 237 via the transfer
transistor 236, is turned into a voltage signal by a circuit (not
shown), and is output as an imaging signal.
[0044] Additionally, a portion of light incident on the solid-state
imaging device 200 is transferred through the first substrate 210
via the light pipe 216, and is incident on a photoelectric
conversion unit 225 of the second substrate 220. This light is
photoelectrically converted by the photoelectric conversion unit
225, and a signal charge according to the quantity of light is
generated. The signal charge generated by the photoelectric
conversion unit 225 is transferred to the floating diffusion layer
238 via the multilayer wiring layer of the second substrate 220 and
the multilayer wiring layer of the third substrate 230. The signal
charge transferred to the floating diffusion layer 238 is
transferred to the floating diffusion layer 240 via the transfer
transistor 239, is turned into a voltage signal by a circuit (not
shown), and is output as a light filed signal.
[0045] A portion of light that is incident on the solid-state
imaging device 200 and that is transmitted through the micro lens
201 and the color filter 202 is incident on a light pipe 216
provided at a position according to the angle of incidence on the
micro lens 201. Selecting the light incident on the photoelectric
conversion units 225 in two dimensions by the micro lens 201 and
the light pipes 216 is equal to selecting the light lay angles of
the light incident on the solid-state imaging device 200. Hence, a
signal obtained by a photoelectric conversion unit 225 corresponds
to the light ray angle of the light incident on the solid-state
imaging device 200.
[0046] As described above, according to the present embodiment, the
photoelectric conversion unit 215 for obtaining the imaging signal
and the photoelectric conversion unit 225 for obtaining the light
field signal are arranged on different substrates, respectively.
Thus, it is possible to form the photoelectric conversion unit 215
with a size enough to obtain the imaging signal.
[0047] For this reason, the light field signal can be acquired
without sacrificing the S/N ratio of the imaging signal.
[0048] Additionally, the imaging signal can be read via the
transfer transistor 236 provided at the third substrate 230.
Additionally, a light field signal can be read via the transfer
transistor 239 provided at the third substrate 230. That is, the
imaging signal and the light field signal can be read by one third
substrate 230.
[0049] Moreover, since the reading unit (the transfer transistor
236 and the transfer transistor 239) for reading the imaging signal
and the light field signal is arranged at the third substrate 230
that is different from the second substrate 220 where the
photoelectric conversion units 225 are arranged, the degree of
freedom of a circuit for processing the imaging signal and the
light field signal can be enhanced. Thereby, for example, the size
of the transistors can be increased or the number of transistors
can be increased. Additionally, if the diffusion region of a
semiconductor is exposed, noise is generated, and the noise is
mixed in the signal charge. However, since the floating diffusion
layers 238 and 240 are formed at the third substrate 230, the
floating diffusion layers 238 and 240 are not easily exposed as
compared to the first embodiment in which the floating diffusion
layers 127 and 131 are formed at the second substrate 120,
generation of the noise can be reduced.
[0050] Additionally, as the light pipe 216 is provided, light can
be guided to the photoelectric conversion unit 225 while reducing
the crosstalk of light incident on the solid-state imaging device
200. Moreover, the light pipes 216 can be realized by a
post-process of a semiconductor process by forming the light pipe
216 of an insulator.
Third Embodiment
[0051] Next, in a third embodiment of the present invention, an
imaging apparatus equipped with the solid-state imaging device 100
of the first embodiment or the solid-state imaging device 200 of
the second embodiment will be described. FIG. 6 is a block diagram
showing the schematic configuration of the imaging apparatus (for
example, digital single-lens camera) equipped with the solid-state
imaging device 100 of the first embodiment.
[0052] The imaging apparatus 7 shown in FIG. 6 is configured to
have a lens unit section 2, a solid-state imaging device 100, an
image signal processing device 3, a recording device 4, a camera
control device 5, and a display device 6.
[0053] In the lens unit section 2, driving of a zoom, a focus, a
diaphragm, and the like is controlled by the camera control device
5, and a subject image is formed on the solid-state imaging device
100. The solid-state imaging device 100 is driven and controlled by
the camera control device 5, subject light incident on the
solid-state imaging device 100 via the lens unit section 2 is
converted into electrical signals, and image signals according to
the amount of incident light are output to the image signal
processing device 3.
[0054] The image signal processing device 3 processes signal
amplification, conversion into image data, and various corrections,
compression of image data, and the like on the image signals input
from the solid-state imaging device 1. The image signal processing
device 3 uses a memory (not shown) as temporary storage means of
the image data in each processing. The recording device 4 is a
detachable recording medium, such as a semiconductor memory, and
performs recording or reading of the image data. The display device
6 is a display device, such as liquid crystal, which displays an
image that is formed on the solid-state imaging device 1 and is
based on the image data processed by the image signal processing
device 3 or the image data read from the recording device 4. The
camera control device 5 is a control device that controls the
overall imaging apparatus 7.
[0055] Although the imaging apparatus 7 shown in FIG. 6 is equipped
with the solid-state imaging device 100 of the first embodiment, it
is also possible to equip the imaging apparatus with the
solid-state imaging device 200 of the second embodiment instead of
the solid-state imaging device 100.
[0056] As described above, the imaging apparatus of the present
embodiment is equipped with the solid-state imaging device 100 of
the first embodiment or the solid-state imaging device 200 of the
second embodiment. Accordingly, since the photoelectric conversion
unit for obtaining the imaging signal and the photoelectric
conversion unit for obtaining the light field signal are arranged
on different substrates, respectively, the imaging apparatus that
can acquire the light field signal can be provided without
sacrificing the S/N ratio of the imaging signal.
[0057] While preferred embodiments of the present invention have
been described and illustrated above, it should be understood that
these are exemplary of the present invention and are not to be
considered as limiting. Additions, omissions, substitutions, and
other modifications can be made without departing from the spirit
or scope of the present invention. Accordingly, the present
invention is not to be considered as being limited by the foregoing
description, and is only limited by the scope of the appended
claims.
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